Adjustable weight dumbbells are known that use an elongated, cylindrical bar as the handle. An inner collar is inset inwardly from each end of the bar with the collar being releasably fixed to the bar by some type of fastener or holding device. The inset provides a space on each end of the bar that is used to support one or more weight plates on the ends of the bar outboard of the inner collars. After the user stacks a desired number of weight plates on the ends of the bar, the user installs an outer collar on each end of the bar to hold the stacked weight plates on the ends of the bar to prevent the weight plates from sliding off the bar during exercise. The user adjusts the exercise mass of the dumbbell by changing the number of weight plates that are held between the inner and outer collars on each end of the bar. Typically, the weight plates are flat, circular plates having a central bore for slipping the weight plates onto the bar.
To use the dumbbell described above, the user merely grabs the center of the bar between the stacks of weight plates on the ends of the bar. Inherently, the user's hand is positioned centrally between the stacks of weight plates along a centerline of the bar, which is also a centerline of the stacked weight plates. The user can then lift and manipulate the dumbbell in any of the known ways to perform various weight training exercises, such as arm curls, arm presses, etc.
In the past, one manufacturer of dumbbells of the type described above has offered an optional U-shaped handle for converting this type of dumbbell to a kettlebell style. The bottoms of the spaced legs of the U-shaped handle were formed with circular bores that were designed to slide onto the bar that formed the usual handle for the dumbbell. The user would remove weight plates and the inner and outer collars from one end of the bar to provide access to the center of the bar. The user would then slip the U-shaped handle onto the bar from this end of the bar, namely the end of the bar from which the weight plates and collars had been removed, simply by telescoping or inserting the bores in the legs of the U-shape onto the bar and by then sliding the U-shaped handle inwardly to the center of the bar. The removed weight plates and collars could then be replaced onto the end of the bar from which they had been taken.
When so installed as described above, the U-shaped handle was captured between the inner collars on the bar. In addition, the legs of the U-shaped handle were long enough so that the base of the U-shaped handle, namely the connecting piece between the two legs of the handle, was positioned to be parallel to the bar but to be vertically displaced above the weight plates. Thus, the user could now grab the base of the U-shaped handle and swing or manipulate the dumbbell in the manner of a kettlebell. Thus, a standard adjustable weight dumbbell could be converted in this manner to a kettlebell type of exercise device.
Other adjustable weight dumbbells are known which are referred to as selectorized dumbbells, such as that shown in U.S. Pat. No. 5,637,034 as also shown in FIG. 1 of this application. In such a dumbbell, the handle is no longer a simple, cylindrical bar, but has a more complex shape. The handle of this type of dumbbell has a pair of planar ends that are spaced apart from one another but are rigidly joined to one another at least by a central hand grip that extends between the ends and is affixed thereto. In addition to the hand grip, there may be one or more cross tubes that also extend between and unite the spaced planar ends of the handle together. Some type of movable selector is used which coacts with the handle and with a desired number of weight plates disposed in left and right stacks of weight plates. When the selector is moved between different positions relative to the handle, different numbers of weight plates are coupled to the left and right ends of the handle to adjust the exercise mass of the selectorized dumbbell.
In a selectorized dumbbell of the type described above and as shown in FIG. 1 of this application, there is no way to use the U-shaped handle of prior dumbbells with the selectorized dumbbell to provide a kettlebell style of exercise. The U-shaped handle of the prior dumbbell is designed to slip onto a bar from which access can be had from one end of the bar. In the selectorized dumbbell, even if one considers the hand grip a bar, the ends of the hand grip are united to planar left and right ends of the handle thereby blocking access to the hand grip. There is simply no way to slide an auxiliary U-shaped handle onto the hand grip of the handle of the selectorized dumbbell as one is blocked from doing so by either the planar left end of the handle or the planar right end of the handle. It would be an advance in the art to provide some way of converting this type of selectorized dumbbell into a kettlebell type of exercise device.